JP2013047525A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbocharger capable of securing sealing performance between a turbine housing and a bearing housing by a heat insulation board and preventing the corrosion of the bearing housing caused by the adhesion of condensation water.SOLUTION: A circular heat insulation board 50 interposed between the bearing housing 41 and the turbine housing 71 is formed over the entire circumferential direction of an outer end in a radiation direction of the heat insulation board 50, and the heat insulation board has a bent part 51a press-fitted in a bent state in a clearance part 104 formed over the entire circumferential direction of a flange 41a between a turbine housing side end face 41e of the flange 41a and a flange side inner peripheral face 71e of the turbine housing 71. By an elastic force of the bent part 51a, the heat insulation board is closely adhered to a face opposing the heat insulation board 50 of the turbine housing 71 or the bearing housing 41.

Description

  The present invention relates to a turbocharger, and more particularly to a turbocharger having a heat shield plate that shields heat of exhaust gas discharged from an internal combustion engine.

  Generally, a turbocharger includes a turbine provided in an exhaust system of an internal combustion engine and a compressor provided in an intake system of the internal combustion engine. The turbine wheel and the compressor wheel provided in each of the turbine and the compressor are integrated. A single shaft is rotatably connected. That is, when the turbine wheel is rotationally driven by the exhaust of the internal combustion engine, this rotational driving force is transmitted to the compressor wheel via the above-described shaft. As described above, when the compressor wheel is rotated, the air sucked into the internal combustion engine is compressed and forcibly pumped to the combustion chamber of the internal combustion engine. The turbocharger configured as described above can improve the output of the internal combustion engine by performing supercharging using the energy from the exhaust.

Conventionally, a turbocharger as shown in FIG. 8A is known as this type of turbocharger (see, for example, Patent Document 1).
As shown in FIG. 8A, the conventional turbocharger described in Patent Document 1 rotatably supports a turbine housing 132 that rotatably supports a turbine 131 and a shaft 133 that connects the turbine wheel and the compressor wheel. The heat shield plate 136 is disposed between the bearing housing 134 and the turbine housing 132 so as to hold a heat insulating space 135 with respect to the turbine side end surface 134a of the bearing housing 134. The outer edge portion (outer peripheral portion) 136a of the heat shield plate 136 is inserted into the groove portion 139 formed in the inner peripheral portion of the boundary portion with the formed seal surface 138, and the mounting flange 137 and the seal surface 138 are inserted. And the two housings are fastened with bolts. A, so that the bent portion 136b is formed on the outer edge portion 136a of the heat plate 136 shielding the foregoing, retaining the hot plate 136 shielding the fastening of the two housing elastically deformed state between the two housings.

  Accordingly, the turbocharger described in Patent Document 1 described above prevents the heat shield plate 136 from directly contacting the bearing housing 134 with high-temperature exhaust gas that enters the turbine housing 132 and rotates the turbine 131. The heat transfer from the exhaust gas can be suppressed by the heat insulating space 135, and the temperature rise of the bearing housing 134 can be suppressed.

  Further, the bent portion 136b is formed in the outer edge portion 136a of the heat shield plate 136, and the bent portion 136b is supported by the groove portion 139 in an elastically deformed state, thereby preventing the heat shield plate 136 from rattling. Therefore, even when vibration from the internal combustion engine to which the turbocharger is attached or pulsation of exhaust gas sent intermittently from the internal combustion engine acts, wear of the heat shield plate 136 is prevented.

JP-A-7-189724

  However, in the conventional turbocharger as described above, the bent portion 136b is formed on the outer edge portion 136a of the heat shield plate 136, so that the heat shield plate 136 itself can be prevented from rattling. Since the portion 136b is intermittently formed on the outer edge portion 136a of the heat shield plate 136, the sealing performance between the turbine housing 132 and the bearing housing 134 is ensured by holding the heat shield plate 136 in the groove portion 139. Had the problem of being difficult.

  That is, as shown in FIG. 8B, the bent portions 136b of the heat shield plate 136 described above are provided at predetermined locations (three locations in FIG. 8B) of the outer edge portion 136a of the heat shield plate 136. However, there is a portion where the bent portion 136b is not formed in the outer edge portion 136a of the heat shield plate 136. Therefore, high-temperature exhaust gas from the turbine housing 132 side flows into the heat insulating space 135 between the heat shield plate facing surface of the bearing housing 134 and the heat shield plate 136 through a portion where the bent portion 136b is not formed. There is a problem that it is impossible to prevent the high temperature exhaust gas from coming into contact with the bearing housing 134.

  In addition, since the bearing housing is usually cooled by a cooling liquid or the like, condensed water adheres when high-temperature exhaust gas containing water vapor comes into contact with the cooled bearing housing. Therefore, in the conventional turbocharger as described above, due to the above-described problem that the sealing performance by the heat shield plate 136 cannot be ensured, the condensed water as described above adheres to the bearing housing 134. There is a problem that the corrosion of the bearing housing 134 due to the adhesion of the condensed water cannot be suppressed.

  The present invention has been made in order to solve the above-described conventional problems, and can ensure the sealing performance between the turbine housing and the bearing housing by the heat shield plate, and the bearing housing by adhesion of condensed water. An object of the present invention is to provide a turbocharger that can prevent corrosion of the steel.

  In order to achieve the above object, the turbocharger according to the present invention includes: (1) a compressor wheel is disposed on an intake passage of an internal combustion engine, and a turbine wheel coupled to the compressor wheel via a rotating shaft is provided in the internal combustion engine. A turbocharger disposed on an exhaust passage of an engine, which rotatably supports the rotating shaft and has a flange portion formed on the outer peripheral portion over the entire circumference, and accommodates the rotating shaft A bearing housing, an exhaust gas introduction passage communicating with the exhaust passage, an inner peripheral end face attached to the flange portion, and housing the turbine wheel therein, and the bearing housing and the turbine housing. A disc-shaped heat shield plate interposed therebetween, and the turbine housing of the flange portion In the turbocharger in which a gap portion is formed over the entire circumference in the circumferential direction of the flange portion between the end surface and the flange portion side inner peripheral surface of the turbine housing, the heat shield plate is formed of the heat shield plate. A radially outer end is formed over the entire circumference, and has a bent portion that is press-fitted into the gap portion in a bent state, and the heat shield plate is formed by the elastic force of the bent portion. The housing or the bearing housing is configured to be in close contact with the heat shield plate facing surface.

  With this configuration, the bent portion formed over the entire circumference in the radial direction of the heat shield plate is press-fitted in a state bent to the gap portion, so that the heat shield plate can be prevented from rattling. Wear of the heat shield plate due to rattling can be prevented, and the sealing performance between the turbine housing and the bearing housing can be improved over the entire circumference in the radial outer end of the heat shield plate.

  Furthermore, since the heat shield plate can be brought into close contact with the heat shield plate facing surface of the turbine housing or the bearing housing by the elastic force of the bent portion, it is possible to prevent the bearing housing from being exposed to high-temperature exhaust gas containing water vapor, Generation | occurrence | production of condensed water can be suppressed and corrosion of the bearing housing by adhesion of condensed water can be prevented.

  In addition, you may comprise the above-mentioned bending part so that it may be formed in the substantially cross-sectional U shape opened facing the outer peripheral surface of a bearing housing.

  In this case, since the bent portion is formed in a substantially cross-sectional U shape that opens to face the outer peripheral surface of the bearing housing, for example, high-temperature exhaust gas containing water vapor flows from the exhaust gas introduction passage to the gap portion side. At this time, the bent portion opened in a substantially U-shaped cross section is pushed and expanded by being pressed into the gap portion by the internal pressure of the inflowing exhaust gas. Therefore, in addition to the elastic force of the bent part, the bent part is in close contact with the turbine housing side end face and the flange side inner peripheral surface that form the gap due to the internal pressure of the exhaust gas. In addition, the wear of the heat shield plate due to the rattling is prevented more reliably, and the turbine housing and the bearing housing are disposed over the entire circumference of the radial outer end of the heat shield plate in the gap. A sealing property between them can be secured. Further, since the heat shield plate can be brought into close contact with the heat shield plate facing surface of the turbine housing or the bearing housing by the internal pressure of the exhaust gas in addition to the elastic force of the bent portion, the bearing housing is attached to the high-temperature exhaust gas containing water vapor. It can be prevented from being exposed, the generation of condensed water can be suppressed, and corrosion of the bearing housing due to the adhesion of condensed water can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the turbocharger which can ensure the sealing performance between the turbine housing and bearing housing by a heat shield, and can prevent the corrosion of a bearing housing by adhesion of condensed water is provided. it can.

1 is a configuration diagram of a diesel engine to which a variable capacity turbocharger according to an embodiment of the present invention is applied. 1 is a cross-sectional view of a variable capacity turbocharger according to an embodiment of the present invention. It is a side view which shows the variable nozzle mechanism of the variable displacement turbocharger which concerns on embodiment of this invention, (a) shows the side view which looked at the variable nozzle mechanism from the left in FIG. 2, (b) FIG. 3 is a side view of the variable nozzle mechanism viewed from the right side in FIG. 2. It is the elements on larger scale which expanded a part of FIG. It is a figure which shows the structure of the heat shield of the variable capacity | capacitance type turbocharger which concerns on embodiment of this invention, (a) shows the front view which looked at the heat shield from the right direction in FIG. ) Is a cross-sectional view showing an AA cross section of (a). It is a partially expanded sectional view explaining the effect | action of the heat insulation board of the variable capacity | capacitance type turbocharger which concerns on embodiment of this invention. It is sectional drawing of the heat insulation board which shows the other shape of the bending part formed in the radial direction outer end part of the heat insulation board with which the variable capacity | capacitance type turbocharger which concerns on embodiment of this invention is provided. It is a partially expanded sectional view which shows a part of conventional turbocharger.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a diesel engine 1 to which a variable capacity turbocharger 20 according to an embodiment of the present invention is applied.

First, the configuration will be described.
A variable capacity turbocharger 20 as a supercharger is mounted on a vehicle and constitutes a part of a diesel engine 1 as an internal combustion engine. This internal combustion engine may be other than a diesel engine, for example, an internal combustion engine using a liquid such as gasoline or ethanol as fuel.

  As shown in FIG. 1, the diesel engine 1 has an engine specification such as its type and model arbitrarily selected, and is configured by a known diesel engine such as an in-line four cylinder. Specifically, the diesel engine 1 includes an engine body 2, a fuel supply device 3 that supplies fuel to the engine body 2, an intake pipe 4, an air cleaner 5 provided in the intake pipe 4, an intercooler 6, and a throttle. A valve 7, an exhaust pipe 8, an EGR (Exhaust Gas Recirculation) device 9 that recirculates part of the exhaust gas discharged from the engine body 2 into the intake pipe 4, and exhaust gas post-processing provided in the exhaust pipe 8 The apparatus 11 includes a variable capacity turbocharger 20.

  The engine main body 2 includes a cylinder 21, an intake device 22, an exhaust device 23, an injector 24, a common rail 25, and an exhaust injector 26 that injects fuel into the exhaust device 23.

  The cylinder 21 is composed of four cylinders 21a, 21b, 21c, and 21d. An intake device 22 is connected to each of the cylinders 21a to 21d via an intake port (not shown), and an exhaust port (not shown). The exhaust device 23 is connected via

  The intake device 22 has an intake passage and branch portions 22a, 22b, 22c, and 22d that are branched into four at one end. The intake device 22 is connected to the intake pipe 4 at the other end, and is connected to each intake port of the engine body 2 at each end of the branch portions 22a to 22d.

  In the intake device 22, the air supplied from the intake pipe 4 is supplied from the branch portions 22a to 22d to the cylinders 21a to 21d via the intake ports.

  The exhaust device 23 includes branch portions 23a, 23b, 23c, and 23d that are branched into four at one end, and one end of each of the branch portions 23a to 23d is connected to each exhaust port of the engine body 2, and the other end. The branch portions 23a to 23d are gathered and have a collecting pipe 23e connected to the variable capacity turbocharger 20. The EGR device 9 is connected to the collecting pipe 23e, and a part of the exhaust gas discharged from the cylinders 21a to 21d flows into the EGR device 9.

  The injector 24 includes four injectors 24a, 24b, 24c, and 24d, each having a fuel injection nozzle and provided in the cylinders 21a to 21d, and injecting fuel into the cylinders 21a to 21d from the fuel injection nozzle. To make it foggy.

  The common rail 25 has a pressure accumulating portion (not shown) that accumulates high-pressure fuel supplied from the fuel supply device 3, and is connected to the injectors 24a to 24d, and distributes high-pressure fuel to the injectors 24a to 24d. Yes.

  Similarly to the injector 24, the exhaust injector 26 has a fuel injection nozzle and is provided in the collecting pipe 23e. Post-injection of fuel into the exhaust passage of the collecting pipe 23e is performed to add fuel to the exhaust gas. It has become. By this post-injection, the exhaust gas aftertreatment device 11 is heated to increase the treatment efficiency, and the oxidation of deposits such as PM (Particulate Matter) deposited on the exhaust gas aftertreatment device 11 is promoted, I try to prevent clogging.

  The fuel supply device 3 includes a fuel tank and a fuel pump (not shown), and fuel supply pipes 3a and 3b. The fuel in the fuel tank is made high by the fuel pump and is supplied to the common rail 25 and the exhaust injector 26. It comes to supply.

  The intake pipe 4 is composed of a pipe for introducing fresh air drawn from an intake port (not shown) into the intake device 22 and has an intake passage 4a. The intake pipe 4 is connected to the variable capacity turbocharger 20 and is fresh in the intake passage 4a. Is introduced into the intake device 22 via the variable displacement turbocharger 20. Further, fresh air in the intake passage 4 a is purified by an air cleaner 5 provided in the intake pipe 4, and further cooled by an intercooler 6 provided in the intake pipe 4 to increase the density.

  The throttle valve 7 is composed of a throttle valve such as a butterfly valve, for example, and adjusts the amount of fresh air that has passed through the intercooler 6 into the engine.

  The exhaust pipe 8 is a pipe that discharges exhaust gas discharged from the collecting pipe 23e of the exhaust device 23 to the atmosphere, has an exhaust passage 8a, and one end is connected to the collecting pipe 23e. The exhaust pipe 8 is provided with an exhaust gas after-treatment device 11 so that harmful substances in the exhaust gas are removed. Further, the exhaust pipe 8 is provided with a silencer such as a muffler (not shown) on the downstream side of the exhaust gas aftertreatment device 11.

  The EGR device 9 includes an EGR pipe 31, an EGR valve 32, and an EGR cooler 33, and recirculates exhaust gas in the exhaust passage 8a of the exhaust device 23 into the intake passage 4a of the intake device 22. It is like that.

  The EGR pipe 31 has an EGR passage, and an EGR valve 32 is provided on the intake device 22 side of the EGR pipe 31, and an EGR cooler 33 is provided on the exhaust device 23 side of the EGR pipe 31. .

  The opening degree of the EGR valve 32 is controlled by an electronic control unit (ECU: Electronic Control Unit) (not shown) so that the amount of exhaust gas recirculated into the intake passage is adjusted. The EGR cooler 33 reduces the temperature of the recirculated exhaust gas and increases its density.

  The exhaust gas aftertreatment device 11 includes an NSR catalyst (NOx storage-reduction catalyst) 34, a DPNR catalyst (diesel particulate-NOx reduction catalyst) 35, an oxidation catalyst 36, an exhaust temperature sensor 37, a differential pressure sensor 38, A fuel ratio sensor 39 is included.

  The NSR catalyst 34 is configured to contain a NOx occlusion substance, occludes NOx in the exhaust gas when the exhaust air-fuel ratio is lean, and reduces the NOx occluded when the exhaust air-fuel ratio becomes rich. Thus, NOx in the exhaust gas is reduced.

  The DPNR catalyst 35 is made of a porous ceramic coated with a NOx storage reduction catalyst having the ability to oxidize PM. The DPNR catalyst 35 collects PM in the exhaust gas and purifies it simultaneously with NOx in the exhaust gas. ing. During these purifications, PM is oxidized, CO (carbon monoxide) and HC (hydrocarbon) are also oxidized, and NOx is reduced.

  The oxidation catalyst 36 is made of a catalytic metal such as platinum or palladium that has an oxidation activity with respect to various gases, and oxidizes harmful substances in the exhaust gas, for example, HC, to be decomposed into CO2 (carbon dioxide) and H2O (water vapor). It comes to handle.

The exhaust temperature sensor 37 includes a detection element such as a thermistor, and detects a temperature change as a resistance value change.
The differential pressure sensor 38 is composed of a pressure sensor, and detects the differential pressure between the pressure of the exhaust gas upstream of the NSR catalyst 34 and the pressure of the exhaust gas downstream of the DPNR catalyst 35, thereby determining the PM of the DPNR catalyst 35. It is designed to detect clogging.

The air-fuel ratio sensor 39 includes a detection element such as a zirconia element, and detects the oxygen concentration in the exhaust gas by detecting electric power according to the oxygen concentration difference.
Information detected from the exhaust temperature sensor 37, the differential pressure sensor 38, and the air-fuel ratio sensor 39 is sent to an electronic control unit (not shown).

Next, the configuration of the variable capacity turbocharger 20 according to the present embodiment will be described with reference to the drawings.
FIG. 2 is a cross-sectional view of the variable capacity turbocharger 20 according to the embodiment of the present invention. 3 is a side view showing the variable nozzle mechanism of the variable capacity turbocharger 20 according to the embodiment of the present invention. FIG. 3A is a side view of the variable nozzle mechanism as viewed from the left in FIG. (B) shows the side view which looked at the variable nozzle mechanism from the right side in FIG.

  As shown in FIG. 2, the variable displacement turbocharger 20 includes a bearing housing 41, a turbine 42, a compressor 43, an actuator 44, a variable nozzle mechanism 45, and a heat shield plate 50. Then, the turbine 42 is rotated using the energy of the exhaust gas discharged from the exhaust device 23 (see FIG. 1), and the compressor 43 is driven by the motive power to generate fresh air having a pressure higher than the atmospheric pressure by the intake device 22 ( (See FIG. 1).

  The bearing housing 41 is formed on the outer peripheral portion over the entire circumference, and includes a flange portion 41a connected to the turbine 42, a flange portion 41b connected to the compressor 43, and a pair of bearing portions 41c. Yes.

  The pair of bearing portions 41c is constituted by, for example, a full float type bearing, and supports the rotating shaft 62 rotatably. That is, the bearing housing 41 is configured to rotatably support the rotating shaft 62 via the pair of bearing portions 41 c and to accommodate the rotating shaft 62.

  A turbine wheel 73 described later is connected to one end of the rotating shaft 62, and a compressor wheel 83 described later is connected to the other end, and the turbine wheel 73 and the compressor wheel 83 rotate together with the rotating shaft 62. It is supposed to be.

  Further, the bearing housing 41 is provided with a water jacket 41d in the vicinity of the bearing portion 41c so that the vicinity of the bearing portion 41c is cooled and seizure of the rotating shaft 62 is prevented.

  The turbine 42 includes a turbine housing 71 and a turbine wheel 73, and the turbine wheel 73 is connected to the rotary shaft 62.

  The turbine housing 71 is discharged through a scroll passage 71 a for turning the exhaust gas, an annular gas passage 71 b for passing the exhaust gas in the scroll passage 71 a toward the turbine wheel 73, and the turbine wheel 73. An exhaust gas passage 71c through which the exhaust gas passes is formed.

  One end of the turbine housing 71 is connected to the upstream exhaust pipe 8 shown in FIG. 1, and the exhaust passage 8a in the upstream exhaust pipe 8 and the scroll passage 71a communicate with each other. Exhaust gas flows into the scroll passage 71a. On the other hand, the other end portion of the turbine housing 71 is connected to the downstream exhaust pipe 8 shown in FIG. 1, and the exhaust passage 8a and the exhaust gas passage 71c in the downstream exhaust pipe 8 communicate with each other. The exhaust gas in the passage 71c is discharged to the exhaust passage 8a in the exhaust pipe 8 on the downstream side. Further, the gas flow path 71b introduces exhaust gas that has flowed into the scroll passage 71a communicating with the exhaust passage 8a into the turbine wheel 73. The gas flow path 71b in the present embodiment constitutes an exhaust gas introduction passage in the present invention.

  The turbine housing 71 is attached to the flange portion 41a of the bearing housing 41 on the inner peripheral end surface 71d on the compressor 43 side in the axial direction of the rotary shaft 62, and accommodates the turbine wheel 73 therein. ing.

  In the turbine 42, the exhaust gas flowing into the scroll passage 71a from the exhaust passage 8a in the upstream exhaust pipe 8 is introduced into the turbine wheel 73 through the gas passage 71b, and the turbine wheel 73 is caused by the flow pressure of the exhaust gas. Is designed to rotate.

  The compressor 43 includes a compressor housing 81 and a compressor wheel 83, and the compressor wheel 83 is connected to the rotating shaft 62.

  In the compressor housing 81, intake air 81 a that introduces purified air that has passed through the air cleaner 5 shown in FIG. 1 toward the compressor wheel 83, and intake air whose pressure has been increased by the rotation of the compressor wheel 83 is taken in. A discharge passage 81b for discharging to the intake passage 4a of the pipe 4 and an inflow passage 81c for allowing the intake air compressed by the compressor wheel 83 to flow into the discharge passage 81b are formed.

  One end of the compressor housing 81 is connected to the upstream side intake pipe 4 shown in FIG. 1, and the intake passage 4a in the upstream side intake pipe 4 and the introduction passage 81a communicate with each other. The intake air flows into the introduction passage 81a. On the other hand, the other end portion of the compressor housing 81 is connected to the downstream intake pipe 4, and the intake passage 4a and the discharge passage 81b in the downstream intake pipe 4 communicate with each other, and the intake air in the discharge passage 81b. Is discharged to the intake passage 4a in the intake pipe 4 on the downstream side.

  In the compressor 43, the intake air introduced into the introduction passage 81a from the intake passage 4a in the intake pipe 4 on the upstream side is introduced into the compressor wheel 83, and the pressure is increased by the rotation of the compressor wheel 83, so that the inflow passage It is discharged into the discharge passage 81b through 81c.

  The actuator 44 is connected to a drive unit (not shown) and is connected to a variable nozzle mechanism 45 to be described later. The actuator 44 is controlled by the electronic control unit according to the driving state of the vehicle. It is designed to operate.

  As shown in FIGS. 2 to 3A and 3B, the variable nozzle mechanism 45 includes a plurality of vanes 91 disposed in the gas flow path 71 b of the turbine housing 71, and the vanes 91 via a shaft 92. A nozzle plate 93 that is rotatably supported, a unison ring 95 that rotates the shaft 92 via an arm 94 that is fixed to the end of each shaft 92, and a unison ring 95 that is pivotably engaged at one end. A driven link 97 fixed to the link shaft 96 at the other end, a bush 98 provided on the bearing housing 41 to rotatably support the link shaft 96, and an end fixed to the link shaft 96 at the other end. And a drive link 101 fixed to the actuator 44 at a portion.

  In the variable nozzle mechanism 45, a plurality of vane nozzles 45 a that vary the inflow capacity of the exhaust gas are defined by the plurality of vanes 91, and the exhaust gas passes through the plurality of vane nozzles 45 a and the scroll passage of the turbine 42. It flows into the turbine wheel 73 from 71a.

  The variable nozzle mechanism 45 is configured such that the opening degree of the vane 91 is changed by rotating the unison ring 95 and rotating the arm 94 engaged with the unison ring 95 about the shaft 92. Has been. The unison ring 95 is connected to the actuator 44 through a driven link 97, a link shaft 96, and a drive link 101, and the opening degree of the vane 91 is changed by the operation of the actuator 44. By changing the opening degree of the vane 91, the flow rate of the exhaust gas flowing into the gas passage 71 b of the turbine housing 71 and flowing between the vanes 91 and flowing into the turbine wheel 73 can be varied. As a result, the rotational speed of the turbine wheel 73 can be varied, so that the rotational speed of the compressor wheel 83 can be varied, and the supercharging pressure of the intake air compressed by the compressor 43 can be varied.

  The heat shield plate 50 is interposed between the bearing housing 41 and the turbine housing 71 to prevent the high-temperature exhaust gas flowing in from the gas flow path 71b from coming into contact with the bearing housing 41 and to remove the heat of the exhaust gas. It is designed to shield. The details of the heat shield plate 50 will be described later.

Next, the configuration of the heat shield plate 50 will be described in detail with reference to FIG.
FIG. 4 is a partially enlarged cross-sectional view in which a part of FIG. 2 is enlarged. 5 is a diagram showing the configuration of the heat shield 50 of the variable capacity turbocharger 20 according to the embodiment of the present invention. FIG. 5A shows the heat shield 50 from the right in FIG. The seen front view is shown, (b) is sectional drawing which shows the AA cross section of (a).

  As shown in FIG. 4, on the turbine 42 side of the variable capacity turbocharger 20, the outer peripheral surface of the bearing housing 41 including the flange portion 41a, the inner peripheral surface of the turbine housing 71, and the compressor 43 of the nozzle plate 93 (see FIG. 2). The link chamber 102 is defined by the side surface on the) side.

  Here, there is not a little gap between the inner peripheral surface of the turbine housing 71 that defines the link chamber 102 and the outer peripheral end surface of the nozzle plate 93. For this reason, when the exhaust pressure in the scroll passage 71a rises and becomes higher than the exhaust pressure in the link chamber 102, the high-temperature exhaust gas including water vapor that circulates in the scroll passage 71a passes through the gas passage 71b and the turbine wheel 73. May be introduced into the link chamber 102 through a gap between the inner peripheral surface of the turbine housing 71 and the outer peripheral end surface of the nozzle plate 93.

  As described above, since there is a possibility that the high-temperature exhaust gas containing water vapor flows into the link chamber 102, the high-temperature exhaust gas containing water vapor directly contacts the outer peripheral surface of the bearing housing 41 that defines the link chamber 102. In order to avoid this, a heat shield 50 is provided so as to be in close contact with the surface of the bearing housing 41 facing the link chamber 102.

  Further, a gap 104 is formed between the turbine housing side end surface 41e of the flange portion 41a of the bearing housing 41 and the flange portion side inner peripheral surface 71e of the turbine housing 71 over the entire circumferential direction of the flange portion 41a. ing.

  As shown in FIGS. 5 (a) and 5 (b), the heat shield plate 50 is made of a member having a low thermal conductivity, such as a disk-shaped stainless steel plate, and forms a link chamber 102. 41 includes an annular bottom surface portion 51 that covers the flange portion 41 a of the cylinder 41 and a cylindrical side surface portion 52 that covers the outer peripheral surface of the bearing housing 41 that defines the link chamber 102.

A bent portion 51 a that is bent toward the turbine housing 71 is formed at the radially outer end of the bottom surface portion 51 of the heat shield plate 50 over the entire circumference. The bent portion 51 a is formed in a substantially U-shaped cross section that opens to face the outer peripheral surface of the bearing housing 41 and is press-fitted into the gap portion 104 in a bent state. That is, the heat shield plate 50 has a gap portion so as to be in close contact with the turbine housing side end surface 41e and the flange portion side inner peripheral surface 71e forming the gap portion 104 at the radially outer end portion by the elastic force of the bent portion 51a. While being held by 104, the sealing performance in the gap 104 is ensured over the entire circumference in the radial outer end of the heat shield 50 (see FIG. 4).
Further, the heat shield plate 50 is brought into close contact with the heat shield plate facing surface of the bearing housing 41 by the elastic force of the bent portion 51a (see FIG. 4).
In addition, a link shaft hole 51 b for allowing the link shaft 96 in the variable nozzle mechanism 45 to pass is formed in the bottom surface portion 51.

  On the other hand, the side surface portion 52 is formed in a cylindrical shape extending in the vertical direction (the axial direction of the rotary shaft 62) from the radially inner end portion of the bottom surface portion 51, and covers the outer peripheral surface of the bearing housing 41. It has become. Further, an annular convex portion 52 a that protrudes radially inward is formed in the vicinity of the distal end portion of the side surface portion 52, and this annular convex portion 52 a is formed on the outer peripheral surface of the bearing housing 41. By being pressed, the heat shield plate 50 is held against the bearing housing 41. Further, the annular convex portion 52 a ensures a sealing property between the heat shield plate 50 and the outer peripheral surface of the bearing housing 41 at the tip of the side surface portion 52 of the heat shield plate 50.

Next, the action of the bent portion 51a formed at the radially outer end portion of the bottom surface portion 51 of the heat shield plate 50 will be described with reference to FIG.
FIG. 6 is a partially enlarged sectional view for explaining the operation of the heat shield 50 of the variable capacity turbocharger 20 according to the embodiment of the present invention.

  As shown in FIG. 6, when the bent portion 51a is press-fitted into the gap portion 104, the heat shield plate 50 has a gap portion 104 at the radially outer end due to the elastic force of the bent portion 51a. Is held in the gap 104 so as to be in close contact with the turbine housing side end surface 41e and the flange side inner peripheral surface 71e, and the sealing performance in the gap 104 is the circumferential direction of the radially outer end of the heat shield plate 50. Secured over the entire circumference. Thereby, even if the high-temperature exhaust gas containing water vapor flows into the link chamber 102, the sealing performance in the gap 104 can be improved.

  Further, when a high-temperature exhaust gas containing water vapor flows into the link chamber 102, the internal pressure of the exhaust gas as shown by the arrows in the drawing is applied to the inner peripheral surface of the bent portion 51a. The bent portion 51a is expanded outwardly when the internal pressure of the exhaust gas is applied. Thereby, in addition to the elastic force of the bending part 51a formed in the substantially cross-sectional U-shape in the bending part 51a formed over the perimeter of the circumferential direction of the radial direction outer end part, the heat shield 50 is exhausted. By the internal pressure of the gas, the turbine housing side end surface 41e and the flange portion side inner peripheral surface 71e, which form the gap 104, are more closely attached. For this reason, even when high-temperature exhaust gas containing water vapor flows into the link chamber 102, the sealing performance in the gap 104 can be ensured.

  As described above, in the variable capacity turbocharger according to the embodiment of the present invention, the bent portion 51a formed at the radially outer end portion of the heat shield plate 50 over the entire circumference is bent into the gap portion 104. Therefore, the heat shield plate 50 can be prevented from rattling, the wear of the heat shield plate 50 due to the rattle can be prevented, and the radial outer end of the heat shield plate 50 in the circumferential direction. Thus, the sealing performance between the turbine housing 71 and the bearing housing 41 can be improved.

  Further, since the heat shield plate 50 can be brought into close contact with the heat shield plate facing surface of the turbine housing 71 or the bearing housing 41 by the elastic force of the bent portion 51a, the bearing housing 41 is exposed to high-temperature exhaust gas containing water vapor. Therefore, the generation of condensed water can be suppressed, and corrosion of the bearing housing 41 due to the adhesion of condensed water can be prevented.

  In addition, since the bent portion 51a is formed in a substantially U-shaped cross section that opens to face the outer peripheral surface of the bearing housing 41, when the high-temperature exhaust gas containing water vapor flows into the link chamber 102, this exhaust The bent portion 51a opened in a substantially U-shaped cross section is pushed and expanded by being pressed into the gap portion 104 due to the internal pressure of the gas. Therefore, the bent portion 51a is in close contact with the turbine housing side end surface 41e and the flange portion side inner peripheral surface 71e forming the gap portion 104 due to the internal pressure of the exhaust gas in addition to the elastic force of the bent portion 51a. The backlash of the plate 50 is surely prevented, the wear of the heat shield plate 50 due to this backlash is prevented more reliably, and the circumferential portion of the radial outer end portion of the heat shield plate 50 in the gap portion 104 is covered. Thus, the sealing performance between the turbine housing 71 and the bearing housing 41 can be ensured. Furthermore, since the heat shield plate 50 can be brought into close contact with the heat shield plate facing surface of the turbine housing 71 or the bearing housing 41 by the internal pressure of the exhaust gas in addition to the elastic force of the bent portion 51a, the high-temperature exhaust gas containing water vapor It is possible to prevent the bearing housing 41 from being exposed to the water, thereby suppressing the generation of condensed water and preventing the corrosion of the bearing housing 41 due to the adhesion of the condensed water.

  In the present embodiment, the heat shield plate 50 is configured to be in close contact with the heat shield plate facing surface of the bearing housing 41 by the elastic force of the bent portion 51a. May be configured to be in close contact with the heat shield plate facing surface of the turbine housing 71 including the heat shield plate facing surface of the nozzle plate 93 that defines the link chamber 102. In this case, when the high-temperature exhaust gas containing water vapor flowing through the scroll passage 71a is introduced into the turbine wheel 73 through the gas passage 71b, the inner peripheral surface of the turbine housing 71 and the outer peripheral end surface of the nozzle plate 93 It is possible to prevent the fluid from flowing into the link chamber 102 through the gap therebetween. Thereby, it is possible to prevent the high-temperature exhaust gas containing water vapor from directly contacting the outer peripheral surface of the bearing housing 41 that defines the link chamber 102.

  In addition, in the variable capacity turbocharger 20 according to the present embodiment, the bent portion 51a having a substantially U-shaped cross section is applied. However, the present invention is not limited to this, and sealing performance in the gap portion 104 is ensured. Any shape can be used as long as it can be performed. For example, a bead structure having a generally U-shaped cross section as shown in FIG. 7 may be adopted.

  That is, as shown in FIG. 7, a bent portion 121 a having a substantially cross-sectional shape may be formed on the radially outer end of the bottom surface portion 121 of the heat shield plate 120 over the entire circumference in the circumferential direction. The bent portion 121a is bent in a substantially cross-sectional shape toward the turbine housing 71 and is press-fitted into the gap portion 104 in a bent state similar to the heat shield plate 50 described above. (See FIG. 4).

  Thus, the heat shield plate 120 is press-fitted in a state where the bent portion 121a formed on the outer circumferential end of the radial direction is bent in the gap portion 104. And the wear of the heat shield 120 due to the rattling can be prevented, and the seal between the turbine housing 71 and the bearing housing 41 over the entire circumference in the radial outer end of the heat shield 120. Can be improved.

  Further, since the heat shield plate 120 can be brought into close contact with the heat shield plate facing surface of the turbine housing 71 or the bearing housing 41 by the elastic force of the bent portion 121a, the bearing housing 41 is exposed to high-temperature exhaust gas containing water vapor. Therefore, the generation of condensed water can be suppressed, and corrosion of the bearing housing 41 due to the adhesion of condensed water can be prevented.

  In the present embodiment, the example in which the present invention is applied to the variable displacement turbocharger 20 that employs the variable nozzle mechanism 45 has been described. However, the present invention is not limited to this, and for example, a turbocharger that does not employ the variable nozzle mechanism. You may make it apply this invention to.

  In addition, the embodiment disclosed this time is illustrative in all respects, and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the variable capacity turbocharger according to the present invention can ensure the sealing performance between the turbine housing and the bearing housing by the heat shield and prevent the corrosion of the bearing housing due to the adhering condensed water. The present invention is useful for all turbochargers having a heat shield plate that shields the heat of exhaust gas discharged from an internal combustion engine.

  DESCRIPTION OF SYMBOLS 1 ... Diesel engine (internal combustion engine), 4a ... Intake passage, 8a ... Exhaust passage, 20 ... Variable displacement turbocharger (turbocharger), 41 ... Bearing housing, 41a, 41b ... Flange part, 41e ... End face on the turbine housing side 50, 120 ... heat shield plate, 51, 121 ... bottom face part, 51a, 121a ... bent part, 52 ... side part, 62 ... rotating shaft, 71 ... turbine housing, 71b ... gas flow path (exhaust gas introduction passage), 71d ... inner peripheral end surface, 71e ... flange side inner peripheral surface, 73 ... turbine wheel, 83 ... compressor wheel, 102 ... link chamber, 104 ... gap

Claims (1)

A compressor wheel is disposed on an intake passage of the internal combustion engine, and a turbine wheel connected to the compressor wheel via a rotation shaft is a turbocharger disposed on the exhaust passage of the internal combustion engine,
A bearing housing that rotatably supports the rotating shaft and has a flange portion formed on the outer peripheral portion over the entire circumference, and accommodates the rotating shaft;
A turbine housing having an exhaust gas introduction passage communicating with the exhaust passage, an inner peripheral end face attached to the flange portion, and housing the turbine wheel therein;
A disk-shaped heat shield disposed between the bearing housing and the turbine housing;
In the turbocharger in which a gap portion is formed over the entire circumference in the circumferential direction of the flange portion between the turbine housing side end surface of the flange portion and the flange portion side inner peripheral surface of the turbine housing.
The heat shield plate has a bent portion that is formed in the radially outer end of the heat shield plate over the entire circumference and is press-fitted in a bent state in the gap portion, and the bent portion The turbocharger is characterized in that the heat shield plate comes into close contact with the heat shield plate facing surface of the turbine housing or the bearing housing by the elastic force of the turbocharger.

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